下图为脉冲调制器电路简图，图中人工线开关、充电、反峰、阻尼二_爱下问搜题

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问题问答题简答题

下图为脉冲调制器电路简图，图中人工线开关、充电、反峰、阻尼二极管这些组件各起什么作用？

答案

参考答案：

①双人工线开关用于不同的脉宽选择；

②充电二极管起到放电隔离的作用；

③反峰二极管用于泄放人工线放电结束后产生的负电压，同时也为了防止负载短路或打火时人工线过压；

④阻尼二极管用来消除放电结束时脉冲变压器初级感应出的反向电压向人工线反向充电，同时抑制由于漏感和寄生电容引起的震荡。

多项选择题

急性腹膜炎的病人，取半卧位的目的是什么

A．使脓液集中盆腔便于引流

B．避免膈肌压迫、有利呼吸和循环

C．减少毒素

D．减少肠粘连的发生

完形填空

When I walked into the house after school, the first thing I noticed was a box with items I recognized from my dad’s office.
“What are you doing at home?” I asked casually.
“Andrew, I was      today,” he answered quietly.
I was sure he was joking. “No, you weren't. Why are you     at home?”
Then I noticed his     and realized he was telling me the truth. My father has always been a hard worker and prided himself on his career.     our family has been his joy, and I guess I have    his work for granted.
My father’s unemployment     many changes in our lives. For starters, he was at home all the time, which meant my bed had to be    , my room cleaned up, and my     done right after school. I would come home every day to find him at the computer     jobs. I began to notice how    he seemed, and how losing his job affected his self-esteem, though he tried to be    . For the first time, I    my dad as vulnerable (易受伤的). He asked my brother and me to    less. I gave up my pocket money,      it wasn’t much. I felt I was doing the right. I also found a part-time job.
After several difficult months of searching, my dad    to go in a totally different direction. He    that he never wanted to be laid off again, so he was going to start his own business. Day by day, I watched him     it, and I admired how much time and   he expended. I     knew he was a hard worker, but watching him in action really affected me.
Although this was one of the   experiences for our family, it taught me a lot about dealing with adversity (逆境), and will be my foundations for success.

D．seriousness

B．brought about

A．falling into

D．searching for

A．disappointed

D．appropriate

C．even though